Telephone system



July 15, 1941. I. MOLNAR TELEPHONE SYSTEM 7 Filed Dec. 29, 1939 5Sheets-Sheet 4 w e F 0 M M 7 8 Win n 4/..F 3 R WM m 8 0 C 4 W 4 C 4 0 5L A 5 R M P. 5 R 1 8 n 0 4 5 L m 0 2 w 2 1Q; 3 3 2 V W INVENTOR ImreMal/'70!" BY ATTORNEYS Patented July 15, 1941 TELEPHONE SYSTEM ImreMolnar, Chicago, Ill., assignor to Associated Electric Laboratories,Inc., Chicago, Ill., a corporation of Delaware Application December 29,1939, Serial No. 311,546

57 Claims.

The present invention relates to telephone systems and more particularlyto improvements in apparatus for handling branch exchange calls of aspecial character.

As explained in Patent No. 1,816,634, Carpenter et al., granted July 28,1931, and Patent No. 1,841,093, Dahl, granted January 12, 1932, incertain' branch exchange installations a large part of the incomingcalls are of a special character. For example, in large departmentstores a major portion of the incoming calls are for the purpose ofplacing orders or represent requests for information concerning theprice of the merchandise on sale. In order more expeditiously to handlethe calls incoming to a branch exchange of this type it is desirable tosegregate the calls of special character from the other calls and toroute the calls of special character to special informa tion or orderoperators positions, which positions are staffed with attendantsqualified to dispatch the desired information. In the two patents citedabove, apparatus is provided for the general purpose just mentioned, thearrangement being such that all of the calls of special character arefirst stored in a call storage circuit and are then released fromstorage to the special operators positions in the same order as they arestored. This arrangement not only requires an extremely complicated andextensive switching arrangement in association with the specialoperators positions, but is open to the objection that the calls aredelayed somewhat due to the extensive switching operations required tofirst store the calls and then release the calls from storage.

It is an object of the present invention, there- 'fore, to provide in atelephone system improved special call handling facilities of thecharacter described which are of simple and economical arrangement, arepositive and reliable in operation and are so arranged that the specialcalls are normally routed directly to the special operators positions solong as any of the special operators positions are idle.

It is another object of the invention to provide improved special callhandling facilities of the character described wherein provisions aremade for storing the special calls only when the number of special callsexisting at any one time exceeds the call handling capacity of thespecial operators positions.

It is a further object of the invention to provide improved special callhandling facilities of the character described wherein the call storagecircuit is so arranged that the excess stored calls are released fromstorage and routed to the special operators positions in the same orderas they were stored.

It is another object of the invention to provide an improved callstorage arrangement wherein exceedingly simple provisions are made forpositively preventing undue delay in releasing calls from storage andfor normally preventing excess calls from obtaining preferred storagepositions.

It is a further object of the invention to provide a call storagecircuit of the character described which is so arranged that excesscalls may be permitted to obtain preferred storage positions, wherebyunder certain conditions of heavy trafiic all of the available callstorage positions of the circuit may be utilized.

It is still another object of the invention to provide in a telephonesystem, improved special call handling facilities of the characterdescribed wherein provisions are made for readily transferring the callsof special character from the special operators positions to the regularbranch exchange switchboard and for routing calls directly from thespecial operators positions to the branch exchange switchboard.

It is astill further object of the invention to provide in a telephonesystem including special call handling facilities of the characterdescribed, an improved arrangement whereby all of the special calltrunks, the call storage circuit and the special operators positions maybe supervised from a supervisory operators position and the call storageapparatus may be controlled from the supervisory operators position.

In the illustrated embodiment of the invention, there is providedatelephone system which comprises a central exchange and a branchexchange area including regular'branch exchange facilities. Thesefacilities comprise the usual branch exchange switchboard at which areterminated a plurality of trunks which extend to switching equipment inthe central exchange. The system further comprises additional apparatuswhich is adapted to handle the calls of special character routed fromthe central exchange to the branch exchange area. This additionalapparatus comprises a plurality of special operators positions and'aplurality of special call trunks which extend from the central exchangeand terminate in the branch exchange area in trunk circuits, each ofwhich includes a position finder having access to all of the specialoperators positions. The arrangement of the trunk circuit apparatus issuchthat calls originating on the associated trunks in the centralexchange are automatically routed through the associated positionfinders directly to idle ones of the special operators positions so longas any of these positions are idle. For the purpose of storing excess oroverflow calls until such time as special operators positions areavailable, thereis provided a call storage circuit which is commonlyassociated with the various trunk circuits and includes a call storageposition distributor and call storage release means. In order to permitthe transfer of special calls from the special operators positions tothe regular branch exchange switchboard, a plurality of transfer trunksare provided, which extend from the trunk circuits just mentioned to thebranch exchange operator's switchboard. The transfer trunks are utilizedsolely to transfer incoming special calls to the branch exchangeoperators switchboard, an additional group of trunks being provided forenabling the special operators to extend calls from their respectivepositions to the regular branch exchange switchboard. More specifically,the additional trunks, just mentioned, individually terminate inposition finder switches which have access to the special operatorspositions and have commonly associated therewith a distributor whichfunctions to allot the position finders and associated trunks for use ina predetermined order.

The arrangement of the call storage circuit and of the associated trunkcircuits individual to the special call trunks is such that stored callsare released from storage in the same order as they are stored. Moreparticularly, each.of the trunk circuits is provided with a storageposition finder having positions individually corresponding to thestorage positions of the storage position distributor and the callrelease positions of the storage release means. The arrangement is suchthat the storage finders are operated in response to calls initiated onthe associated trunks when all of the special operators positions arebusy, means controlled by the storage distributor being provided forstopping the storage finders in different positions whereby the excesscalls are stored in a predetermined order. Additional apparatuscontrolled Jointly by the storage release means and the storage positionfinders and operative in accordance with the settings of the storagefinders, are provided for routing the stored calls to the specialoperators positions in the same predetermined order as the specialoperators positions are released or become idle. In order to prevent anyunnecessary elapse of time in releasing calls from storage, controlapparatus is provided for preventing the storage release means fromoperating through a position occupied by the position of the storageposition distributor. Additional control apparatus is provided fornormally preventing the storage position distributor from operatingthrough a position occupied by the storage release means, thereby toprevent later initiated special calls from obtaining preferred storagepositions. The arrangement is such that the last-mentioned controlapparatus may be rendered inactive, whereby storage positions of thestorage distributor which correspond to abandoned stored calls may beutilized in storing additional calls. More specifically, thelast-mentioned control apparatus is under the control of a supervisoryoperator whose function it is to maintain supervision of the variousspecial operators positions and the special call trunks having access tothese positions. To this end. various supervisory lamps are provided atthe supervisory operators position and Provibranch exchange area 20there are provided a plurality of branch exchange trunks, one of sionsare made whereby the supervisory operator may monitor any connectionestablished to any one of the special operators positions. Among thesupervisory lamps provided at the supervisory operator's position areincluded a group of call storage lamps which are individual to theseveral special call trunks, the arrangement being such that each ofthese lamps is energized when a call, present on the associated trunk,is placed in storage. Further, the control arrangement for the callstorage lamps is suchthat each lamp is deenergized when a call stored onthe associated trunk is abandoned prior to its release from storage. Byvirtue of this arrangement, the

1 supervisory operator may maintain a close check upon the number ofcalls in storage and ascertain the advisability of utilizing vacatedcall storage positions of the call storage distributor to storeadditional calls.

Further features of the invention pertain to the particular arrangementof the circuit elements whereby the above-outlined and additionaloperating features are attained.

The novel features believed to be characteristic of the invention areset forth with particularity in the appended claims. The invention, bothas to its organization and method of operation, together with furtherobjects and advantages thereof will best be understood by reference tothe specification taken in connection with the accompanying drawings inwhich Figure 1 schematically illustrates a telephone system havingincorporated therein the features of the invention as briefly outlinedabove; Fig. 2 illustrates the manner of assembling the remaining figuresof the drawings to form a unified system; and Figs. 3 to 6, inclusive,illustrate the details 1of the apparatus schematically shown inReferring now more particularly. to Fig. 1 of the drawings, thetelephone system there illustrated comprises a central exchange l0 and abranch exchange area' 20 within which are located the substations of adepartment store, or the like. The central exchange l0 may be of anydesired type; that is, it may be of the manual type, in which case, thesubscribers and trunk lines extending thereto are terminated in linemultiples at the operators switchboard in the usual manner.Alternatively, the exchange ll may be of any desired automatic type, inwhich case, connections are established between the lines extendingthereto through the provision of dial controlled automatic switchingapparatus. This exchange is arranged to serve a large number of centralomce subscribers lines, one of which is indicated at H as extending tothe central oflice subscriber's substation A. For the purpose of routingregular substation-to-substation calls between the central oiiice andthe which is indicated at I2. This trunk has a trunk circuit l3 ofconventional arrangement associated therewith and terminates at a jack Mwhich is provided at one of the operators positions forming a part ofthe branch exchange operator's switchboard. This switchboard is providedfor the purpose of serving the regular branch exchange substationslocated within the area 2|,

- one such substation B being connected to a substation line I! whichterminates at the branch exchange switchboard in a jack l1 and hasassociated therewith a line circuit Ii through operation of which callsinvolving the line l5 may be supervised. 4

In order to handle calls of special character routed from the centraloflice subscribers substations through the central exchange I 0 to thebranch exchange area 20, a plurality of special call trunks, one ofwhich is indicated at l8, are provided. Assuming that the centralexchange In is of the manual type, these trunks extend from theoperators switchboard in the central exchange I 0 to the branch area 20where they terminate in trunk circuits individual thereto. These trunkcircuits have access to a group of special operators positions. In thecase under consideration wherein it is assumed, for purposes ofexplanation, that the branch exchange area 20 constitutes a departmentstore or other merchandise establishment, the special operatorspositions may be provided for the purpose of taking orders from thecentral office subscribers. For convenience in describing the apparatus,the special call trunks will be referred to hereinafter as order trunks,the trunk circuits associated therewith will be referred to as ordertrunk circuits, and the special operators positions will be referred toas order operators positions. More specifically, the order trunk l8terminates in the branch exchange area 20 in an order trunk circuit I 9which has access to a group of order operators positions including theposition 2|. Under certain circumstances and, more particularly, whenall of the order operators positions are not staifed, the volume oftrafiic over the order trunks may be in excess of the call handlingcapacity of those order operators positions which are attended. In orderto hold such excess calls until such time as an order operators positionis released, there is provided, in common association with the severalorder trunk circuits, a call storag circuit 3| which functions to storethe excess calls in the order of their initiation and to release thestored calls from storage in the same order, as the order operatorspositions become idle. For the purpose of enabling the order operatorsto transfer calls from their positions to the branch exchangeswitchboard, whereby they may be extended to the regular branch exchangesubstations, there are provided a group of transfer trunks, one of whichis indicated at 22 as extending from the order trunk circuit l9 to ajack 23 located at the branch exchange operators switchboard. This groupof trunks can only be used for transfer purposes. Accordingly,additional means comprising a second group of trunks including the trunk28 is provided for enabling the order operators to route calls directlyfrom their positions to the branch exchange switchboard. Morespecifically, these additional trunks terminate in position finderswhich have access to the various order operators positions and haveassociated therewith a position finder distributor 30 which functions toallot the additional trunks and associated position finders for use in apredetermined order. Thus, the trunk 26 terminates at the branchexchange switchboard in a jack 28 and extends to a position finder 29having access to all of the order operators. positions. For the purposeof supervising calls routed by way of the order trunks to the orderoperators positions there is provided a supervisory operators position32 at which are located signal lamps for indicating whether or not theorder operators positions are staffed and, if staffed, whether idle orbusy, and also for identifying those of the order trunks which areoccupied with calls in storage.

Neglecting for the present the particular arrangement 0f the circuitelements embodied in the apparatus schematically illustrated in Fig. 1and considering the operation of the system generally, it will beapparent that interexchange traific between the central oflicesubscribers substations and the regular-substations provided inthebranch exchange area 20 are handled by the regular branch exchangefacilities including the branch exchang operators switchboard and thegroup of trunks of which the trunk l2 forms a part. To thi end, thebranch exchange operators switchboard is assigned a particular directorynumber which is different from the directory number assigned to theorder operators positions. By virtue of this directory numbering schemethe special or order trunk calls may be segregated in the centralexchange and routed by way of the order trunks to idle ones of the orderoperators positions. For example, a call routed over th order trunk l8may, through operation of the order trunk circuit Ill, be routed to theorder operators position 2|. If the order operator attending thisposition is unable to give the calling subscriber the desiredinformation, she may cause the call to b .transferred to one of theregular substations provided in the branch exchange area 20 by operatinga transfer key located at her position, thereby to signal over thetransfer trunk 22 the branch exchange operator attending the position atwhich the trunk 22 is terminated. The branch exchange operator may, inturn, route the call to the desired substation, such, for example, asthe substation B. After a call transfer of this character is made theorder operator attending the position 2| may remain connected to theestablished three-way connection or may retire from the connection andrelease her position for utilization in the handling of additionalcalls. If an operator attending one of the order operators positions,such, for example, as the position 2|, finds it necessary in handling aninquiry to look up certain information and then call a central ofiicesubscriber, she may secure the desired connection by seizing one of thetrunks assigned for use by the position finder distributor 30, such, forexample, as the trunk 26, thereby to route a connection from herposition to a position at the branch exchange switchboard. From thislatter position the call may be routed over one of the regular branchexchange trunks and through the central exchange ID to the desiredsubstation. In a similar manner the order operators may route callsdirectly from their positions to the regular substations located in thbranch exchange area, such calls being handled by the operator oroperators attending the branch exchange switchboard. In the event all ofthe order operators positions become busy at the same time and specialcalls routed over the order trunks continue to arrive, operation of thecall storage circuit 3| is initiated whereby the excess calls are storedin the order of their initiation. As th order operators positions arethereafter released and rendered available for use in handling othercalls, the call storage circuit 3| in cooperation with the associatedtrunk circuits functions to release the stored calls from storage in thesame order as they are stored. Supervision of the order operatorspositions and of the special calls handled at these positions is underthe control of a super. visory operator attending the position 32.

' I" and a plurality of associated control relays and control circuits.The switches 360 and 400 are of the well-known rotary type and may be ofany desired commercial construction. The number or contact pointsprovided in the position finder switch 400 is determined by the numberof available order operators positions, each setting of this switchbeing individual to a particular order operator's position. Similarly,the number of contact points provided in the storage position finderswitch 360 is determined by the number of storage positions available inthe call storage circuit 2|. In the arrangement illustrated, twenty-fourcall storage positions ar available in this circuit and hencetwenty-five sets of contact points are provided in the rotary switch360, the first set of contact points being reserved as the normal orhome position of this switch. The control equipment associated with thetwo switches 360 and 400 comprises a line relay R300 which is normallybridged across the conductors of the order trunk I8 in series with acondenser Ill and is arranged to operate when energized with eitheralternating or direct current. This equipment further comprises aslow-to-operate position finder start relay Bill), a pair of callstorage control relays R320 and R330, a combined cell transfer and trunkrelease relay R340 which is provided with two operating positions inaddition to its normally released position, and a combined finder stopand line switching relay R250.

The apparatus provided at the order operator's position 2| comprises aninduction coil I which is connected to a pair of talking conductors C492and C493, these conductors being terminated in corresponding sets orcontacts in the position finder switches individual to the various trunkcircuits. This induction coil has connected thereto transmitter andreceiver jacks 4|! and 4, respectively, which are arranged to receivethe contacts of a multiple plug 2'', The contacts of this plug areconnected in the usual manner to a transmitter 4H and a receiver 2forming an operator's head set. There is also provided at the operatorsposition 2| a relay R00, which is operative to indicate that theposition is staffed, and a slow-to-operate control relay R440. Thelatter relay is arranged to control the energization of a callsignallamp 423 and 'to perform other control operations describedhereinafter. The control equipment provided at the order operators'position III also includes a combined call transfer and trunk circuitrelease key 6 and a branch exchange call key 420, the first of thesekeys being operative to control the transfer of calls from the position2| to the branch exchang switchboard and to control the release of trunkcircuits which are operated when calls are routed by way thereof to theposition 2|. The key 420, on th other hand, is provided for the purposeof routing calls from the order operator's position 2| directly to thebranch exchange switchboard.

As illustrated in the right-hand portion of Fig. 4, the position finder29, which is individual to the trunk 26 extending to the branch exchangeswitchboard. comprises a finder switch 450 of the well-known rotary typeand a line switching relay R480. The number of contact points providedin the finder switch "I is determined by the number of associated orderoperators positions, one set of contact points being'reserved for eachof the order operators positions to which it has access. Operation ofthis position finder and of-the other finders individually associatedwith the other trunks extending to the branch exchange switchboard isunder the control of the position finder distributor 30 which isillustrated in Fig. 6 as comprising a distributor switch 640, also ofthe well-known rotary type, and having positions corresponding to thenumber of position finders available. This distributor also includes aplurality of control relays which may be identified as a slow-to-operatestart relay RBHI, a pulsing relay R830, a relay R820 for controlling theline switching relays of the respective associated position finders, anda slowto-release relay R600 which is operative to delay the trunkhunting operation of the distributor switch 640 for a short timeinterval after a previously selected position finder switch is operatedto seize a calling one or the order operators positions.

As pointed out previously, the apparatus provided at one of the branchexchange operators positions forming a part of the branch exchangeswitchboard comprises the jacks H, 28, I4 and 23 at which the lines ll,26, I2 and 22, respectively terminate. These lines have individuallyassociated therewith call signal lamps 668, 663, 665 and 653,respectively. There is also provided at this branch exchange operator'sposition an operator's cord circuit 860 which may be of conventionalarrangement. This cord circuit is connected to call and answer plugs 652and Gil, respectively, and includes a transmitter 610 and a receiverill.

The call storage circuit 3| is illustrated in Fig. 5 as comprising acall storage distributor switch 500 and a call release switch 5! each ofwhich is of the well-known rotary type and includes twenty-five sets ofcontact points respectively representing twenty-four difi'erent callstorage positions and a blank or unused position. The operation of theseswitches is under the control of associated relay equipment whichcomprises a call storagestart relay R540, a call storage stop relayR530. and a pulsing relay network for the rotary switch H0 whichincludes the relay R520 and the slow-to-release relay R510. A secondslow-to-operatepulsing relay R560 is provided for controlling theoperation of the distributor switch 500. The relay equipment alsoincludes a stop relay R550 which functions to prevent the rotary switchElli from operating to a storage position in advance of that occupied bythe distributor switch 500 all in the manner more fully explainedhereinafter. For the purpose of indicating an all-busy condition of theorder trunks, there is provided an all-trunk's-busy meter 522.

The apparatus provided at the supervisory operator's position 22comprises a plurality of jacks at which are terminated trunk linesbridged across the talking conductors provided in the various orderoperators positions. Thus, a jack I is provided which is connected tothe conductors C482 and C493 constituting the talking conductorsprovided at the order operator's position 2|. There are also provided atthe supervisory operators position 32 a plurality of signal lampsindividual to the order operators positions and to the order trunkswhich enable the supervisory operator to check at all times the condi--tion of the trunks and of the order operators positions. Thus, aposition lamp 425 is provided which is individual to the orderoperator's position 2| and which, when energized, indicates that thisorder operators position is attended. A second lamp 424 individual tothe order operator's position 2| is also provided which, when energized,indicates that the associated position is busy. A third signal lamp 426is provided which is individual to the order trunk l8 and functions,when energized, to indicate that the associated order trunk is occupiedwith a call which has been placed in storage. In order to enable thesupervisory operator to control the call storage circuit 3| inaccordance with the conditions indicated by the energized anddeenergized conditions of the associated trunk call storage lamps, thereare provided two keys 42! and 422, the last of which is operative torender the call storage circuit 3| totally inactive. The key 42!, on theother hand, is provided for the purpose of enabling the storagedistributor switch 500 to be advanced through a position occupied by thecall release switch 5lll, thereby to permit those call storage positionsin the switch 500 which have the connection has been been vacatedthrough the abandonment of stored calls to be filled up with additionalincoming calls.

Traflic between central office and branch exchange switchboard Referringnow more particularly to the operation of the apparatus illustrated inFigs. 3 to 6, inclusive, if a call routed over one of the central oflicesubscribers lines, such, for example, as the line II, to an operatorsposition in the central oflice I0 is to be extended to a substation lineaccessible to the branch exchange switchboard, the central ofliceoperator handling the call may seize the trunk I2 and, by operation ofthe ringing key embodied in her cord circuit, project ringing currentover this trunk for the purpose of energizing an alternating currentrelay bridged across the conductor of this line and included in thetrunk circuit l3. The resulting operation of this alternating currentrelay causes the energization of the call lamp 665 individual to thetrunk l2. The branch exchange operator, upon observing the lightedcondition of this lamp, may answer the call by inserting the plug 66l inthe jack I 4. In response to this operation, a talking circuit iscompleted between the calling subscriber's substation and the branchexchange operators head set, whereby the operator may converse with thecalling subscriber and obtain the identity of the desired branchexchange substation. When the plug 66! is inserted in the jack l4,ground potential is impressed upon the ring contact of the jack l4 tocause the energization and operation of one of the relays included inthe trunk circuit apparatus I3. The resulting operation of this relaycauses the deenergization of the call lamp 6B5in the usual manner. Whenthe plug GBI is inserted in the jack l4, a direct current bridge is alsoestablished between the tip and sleeve contacts of this jack, thereby tocause the operation of a supervisory relay-embodied in the cord circuitin use by the operator handling the call in the central oifice I0.Assuming that the substation B is desired by the calling central oflicesubscriber, the branch ex- .change operator may extend the connection tothe desired substation by inserting the call plug 662 in the jack I! andoperating the ringing key of the cord circuit 660 to cause ringingcurrent to be projected over the line l5 and through the windings of theringer conventionally provided at the substation B. When the call isanswered at the called substation, the branch exchange operator mayretire from the connection and rely upon the supervisory lamps embodiedin the cord circuit 680 to indicate when the connection is ready to bereleased. When either of the two lamps individual to the calling andcalled ends of the connection is illuminated, indicating that releasedat one end thereof, the branch exchange operator may clear out theconnection. For example, if the called party at the substation B hangsup prior to the release of the connection at the calling end thereof thesupervisory lamp of the cord circuit 660 individual to the called isenergized to indicate to the branch exchange may now clear out theconnection by withdrawing the plugs 66l and 662 from the jacks l4 andII, respectively. In response to this operation, the trunk circuit l3and the line circuit l6 are restored to normal in the usual manner andthe bridge circuit established across the conductors of the trunk lineI2 is opened to cause the energization of the disconnect lamp associatedwith the trunk line I! and embodied in the cord circuit in use at theoperator's position in the central ofllce l0. Upon observing the lightedcondition of this lamp, the operator handling the call at the centraloflice may clear out the connection in the usual manner.

In the event thecall is cleared out at the subresponse to this operationa disconnect signal is transmitted over the trunk I2 to the cord circuit660 to cause the energization of the supervisory lamp in the cord 0 *uit660 which is individual to the calling end of the connection.Energization of this lamp serves to inform the branch exchange operatorthat the connection has beenreleased at the calling end thereof and maybe cleared out at her switchboard. To clear out the connection, theoperator withdraws the plugs 6! and 662 from the jacks l4 and II,respectively, whereby the trunk circuit I3 and the line circuit l6 arerestored to normal in the usual manner.

The trunk l2 and the other similar trunks may also be used in routingcalls from the branch exchange switchboard to the subscribers linesterminating at the central ofiice I 0. For examring contact of the jackI"! to complete a circuit for energizing the signal lamp cut-ofi relayconventionally embodied in the line circuit I 6'.

The resulting operation of this relay causes the deenergization of thecall lamp 666. Upon ascertaining that a central oflice call has beeninitiated at the substation B, the P. B. X. operator may forward theconnection to an operators position in the central ofilce I by insertingthe plug 652 in the jack l4 and operating the ringing key embodied inthe cord circuit 660 to project ringing current over the trunk line l2.The resulting operation of the signal device or devices individual tothis trunk line and provided at the operators switchboard in the centraloflice l0 serves to inform one or more of the central oflice operatorsthat a call is present on the trunk, line l2 which should be answered.Upon answering the call the central oilice operator handling the callmay converse with the party at the substation B and ascertain thesubstation desired by the calling party, following which may set up thedesired connection in the manner conventionally followed in manualoflice practice. After the connection has been established, thesupervision and release thereof are exactly the same as set forth abovewith reference to a call routed from a central ofllce subscriberssubstation to one of the branch exchange telephone stations.

Central oflice call to order operators position Each of the orderoperators, when on duty, maintains her telephone set connected to thesubstation circuit apparatus provided at her position. For example, whenan operator is on duty at the order operators position 2| the terminalsof the multiple plug H2 and terminating the cords respectively extendingto the transmitter 4H and the receiver 2, are maintained inserted in thejacks M3 and M4, respectively, so that the transmitter 4| I is bridgedacross one winding of the induction coil 5 in series with a couplingcondenser and the receiver 4 2 is bridged across a portion of the otherinduction coil winding in series with another coupling condenser. Withthe transmitter 4 connected to the terminals of the jack 3, a circuitextending through the plug and jack contacts and the transmitter 4 iscompleted for energizing the relay R430 and for supplying energizingcurrent to the transmitter. With the relay R430 in its operatedposition, a battery marking path is completed, at RA43I, for identifyingthe operators position 2| as idle in the bank contacts of all of theposition finders having access thereto. As explained more in detailhereinafter when the position is occupied with a call this idle markingis removed and a busy ground marking is substituted therefor. Thus,under normal conditions incoming order trunk calls are being handled,certain of the order operators positions are marked as idle and othersare marked as busy in the bank contacts of the position finders. Withthe relay R430 operated, a circuit extending through RA433 is completedfor energizing the position lamp 425 individual to the order operatorsposition 2| and located at the supervisory operators position 32, thusindicating to the supervisory operator that the order operators position2| is attended.

Assuming that certain of the order operators positions are conditionedto receive incoming calls, and further that the trunk line I8 is seizedat the central oifice and ringing current is projected thereover, therelay R300 is energized by the ringing current traversing its winding,the resistor 3|5 and the condenser 3H in series,

Upon operating, the relayv R300 completes, at RA30I, a circuit forenergizing the relay R3l0, this circuit extending from ground by way ofRA30|, RA344, RA32| and the winding of R3|0 to battery. At RA302, therelay R300 prepares a circuit, now open at RA54|, for energizing theupper winding of R320. At RA303, the relay R300 prepares a holdingcircuit for the relay R330. The relay R3|0 operates after an interval toopen, at RA3|4, the prepared operating circuit for R320; to prepare atRA3I3, a test circuit including the lower winding of R350; and tocomplete, at RA3I2, a circuit extending through RA353 and over C311forenergizing the magnet 403 of the position finder switch 400. AtRA3I3, the relay R3|0 also completes a priming circuit for the relayR350, this circuit extending through the resistor 358 and the upperwinding of R350 to battery. The resistance of this priming circuit issuch that R350 does not operate when it is completed. At RA3| the relayR3|0 connects the winding of the relay R300 directly across the lineconductors of the trunk line l8, thereby to cause the operation of ananswer lamp embodied in the cord circuit being used by the callingoperator in the central ofllce I0 and to establish a loop circuitincluding the central exchange battery over which the line relay R300 isheld energized.

Due to the circuit interrupting action of the armature 0 carried by themagnet 409, the position finder switch 400 operates buzzer fashion sothat the wipers thereof are advanced step by step until the contactscorresponding to the first idle order operators position are selected.During this operation of the switch 400 the lower winding of the relayR350 is short circuited so long as the test wiper 401 is passing overcon tacts corresponding to busy order operators positions. Assuming thatthe order operator's position 2| is the first idle position available,operation of the switch 400 is arrested when the wipers of this switchare advanced to the position corresponding to this order operatorsposition. More specifically, when the test wiper 401 engages theassociated test contact individual to the position 2|, theabove-mentioned test circuit is completed, this circuit extending fromground by way of RA3I3, the lower winding of R350, C318, the wiper 401,RA43| and the winding of R440 to battery. When its lower winding isenergized over this circuit the relay R350 first operates to complete,at the X contacts associated with RA354, an obvious path forshortcircuiting the resistor 358, whereby its upper winding is fullyenergized. Following this operation, the relay R350 fully operates toopen, at RA353, the above-traced operating circuit for the magnet 403,thereby to arrest operation of the switch 400 with the wipers of thisswitch standing on the contacts terminating the conductors extending tothe substation apparatus provided at the order operators position 2|. AtRA35| and RA352, the relay R350 connects the conductors of the trunkline l8 through the line wipers 405 and 400 of the line switch 400 tothe line terminals of the induction coil 45|, thus completing a talkingcircuit between the calling central oifice subscriber's substation andthe telephone set in use by the operator attending the position 2|. AtRA355, the relay R350 prepares a circuit traced hereinafter forenergizing the combined call transfer and trunk release relay R340. AtRA355, the relay R350 opens a point in the prepared holding circuit forR330. At

contacts associated with RA344 RA351, the relay R350 removes groundpotential from the marking wiper 368 of the storage posithe circuit. forenergizing the busy lamp 424 provided at the supervisory operatorsposition 32.

' Thus, the trunk circuit apparatus I9 is fully retion 2| groundpotential as connected through the lower winding of R350 and over C318to the wiper 401 is impressed upon the test contacts of all of the otherposition finder switches which correspond to theorder operators position2|, thus identifying this order operators position as busy in thecontacts of the other'position finder switches.

As indicated above, the slow-to-operate relay R440 is energized inseries with the lower winding of the relay R350 immediately the orderoperators position 2| is selected by the position finder switch 400. Therelay R440 operates after an interval to complete, at RA442, an obviouscircuit for energizing the call signal lamp 423, thereby to indicate tothe operator attending the position 2| that an incoming call should beanswered. At RA442, the relay R440 also opens one of the multiple pathsover which ground potential is normally impressed upon the storage startconductor 0483. At RA443, the relay R440 completes an obvious circuitfor energizing the busy lamp 424 provided at the supervisory operatorsposition 32 and individual to the order operator's position 2 l.

Following operation of the relay R350 to establish a talking circuitbetween the calling central ofllce subscribers substation and theoperators position 2|, the order operator attending this position mayconverse with the calling subscriber and give the calling subscriber theinformation desired. In order to initiate the release of the connectionafter the conversation is terminated, the operator attending theposition 2| momentarily actuates the release key M6 to the offnormalposition required to cause engagement of the springs 8. When thesecontact springs are engaged a circuit is completed for partiallyeneregizing the call transfer and trunk release relay R340, this circuitextending from ground by way of the resistor 4| 9, the springs M, thewiper 408, 0319, RA355 and the winding of R340 to battery. Whenenergized over this circuit the relay R340 partially operates to openthe closed without closing the make contacts associated with thisarmature. As a result, the above-traced operating circuit for the relayR3|0 is interrupted and this relay restores to open the holding circuitfor R350; to open a further point in the operating circuit for thedriving magnet 409; and to disconnect the winding of the line relay R300from across the conductors of the trunk line l8, thereby to cause theenergization of a disconnect signal lamp provided in the cord circuit inuse in the central oifice l0 in the usual manner. The relays R300, R350and R440 now restore. Shortly thereafter and when the call transfer'andtrunk release key M6 is released and allowed to return to its normalposition, the springs 8 are opened to open the circuit for partiallyenergizing the transfer and release relay R340, causing this relay torestore. The relay R440, upon restoring opens, at RA442, the circuit forenergizing the call lamp 423; prepares, at RA44I, the path forimpressing ground potential upon the distributor start conductor C480;completes, at RA442, the multiple path, individual to the position 2|,over which ground potential is normally impressed upon the conductorC483; and opens, at RA443,

. operating circuit for the relay R3l0.

stored to normal and the order operators position 2| is again identifiedas idle in the bank contacts of the various position finders havingaccess thereto. When the central oflice operator handling the callobserves the lighted condition If the connection routed over the trunkline 8 to the order operators position 2| is released at the operatorsposition in the central ofiice |0 prior to actuation of the transfer andM6 in the manner set forth in the paragraph, the relay R300 restores'toopen the The relay R3I0, upon restoring, causes the release of therelays R350 and R440 in the manner previously explained. Thus, in thecase where the connection is cleared out at the operators position inthe central oflice l0, the trunk circuit l9 and the operators positioncircuit are fully released without any operation on the part of theorder operator attending the position 2|.

Transfer of order trunk call to branch exchange switchboard In the eventthe order operator attending the position 2| finds it necessary toconverse with a party located at one of the branch exchange substationsin order to obtain the information desired by the calling subscriber, orto connect the calling subscriber directly to one of the branch exchangesubstations, she may route the call to the branch exchange switchboardby operating the transfer and release key 6 to the off-normal positionrequired to cause engagement of the contact springs 4". In response tothis operation the relay R340 is energized over a circuit from which theresistor M9 is excluded and, accordingly, is caused fully to operate.While assuming its fully operated position, the relay R340 completes, atRA344, an obvious holding circuit for the relay R3l0; initiallycompleted operating circuit for the latter relay. At RA342 and RA343,the relay R340 opens the established talking circuit extending betweenthe calling subscribers substation and the'substation equipment providedat the order operators position 2|. At RA34| the relay R340 completes acircuit for energizing the signal lamp 653 provided at' the branchexchange switchboard, this circuit extending from ground by way ofRA34I, C345, the jack-springs 854 and the filament of the lamp 653 tobattery. The energization of the lamp 653 serves to inform the branchexchange operator that a call is present on the transfer trunk 22 whichshould be answered. To answer the call the branch exchange operator mayinsert the answer plug 06| of the cord circuit 660 in the jack 23,thereby to comat the same time opening the Assuming, for example, thatthe substation B is desired by the order operator, the branch exchangeoperator may route the connection to this substation by inserting thecall plug 662 in the Jack I1 and operating. the ringing key provided inthe cord circuit 660 to cause ringing current to be projected over theline l5 for the purpose of energizing the ringer or signal deviceprovided at the substation B. When the call is answered at thesubstation B, the desired talking circuit may be established through theoperators cord circuit 660 between this substation and the substationapparatus provided at the order op erators position 2|. With theapparatus in this condition the operator attending the position 2| mayconverse with the answering party at the substation B to obtain thedesired information, and during the course of the conversation thecalling central oflice subscriber is excluded from the connection. Ifthe operator attending the position 2| desires, she may establish athreeway talking circuit between her substation, the

central ofiice subscriber substation and the substation E. To this end,the transfer and release key 6 is restored to its normal position. Inresponse to this operation the transfer and release relay R340 isreleased to open the completed holding circuit for the relay R310 andtorecomplete the operating circuit for this relay. At RA342 and RA343,the relay R340 connects the conductors of the order trunk l8 to thetalking conductors of the transfer trunk 22, thereby to establish atalking circuit between her station, the calling central oflicesubstation and the substation B. Upon restoring, the relay R340 alsoopens, at RA34I, a further point in the previously traced circuit forenergizing the signal lamp 653. After the connection is establishedbetween the substation B and the substation of the calling centraloffice subscriber in the manner just explained the operator attendingthe order operators position 2| may return from the connection andrelease the trunk circuit 19 and the position circuit individual to theposition 2| by operating the transfer and release key 416 to theposition required to cause engagement of the contact springs 418. Themanner in which the trunk circuit apparatus l9 and the order operatorsposition circuit are released in response to operation of the transferand release key 416 is exactly the same as described previously.Following the release of this apparatus, supervision of the call asextended through the operators cord circuit 660 to the substation B isunder the control of the branch exchange operator, the supervisory lampsprovided in the cord circuit 660 being utilized to indicate when theconnection is no longer desired. In this regard it is pointed out thatan auxiliary direct current bridge is established in the operators cordcircuit 660 between the line conductors of the order trunk 18 when theanswer plug 681 is inserted in the jack 23 and the transfer and releaserelay R340 is restored to normal. Thus, energization of the disconnectlamp associated with the trunk 13 and provided in the cord circuit inuse in the central ofllce I0 is under the control of the branch exchangeoperator. More particularly, if the branch exchange operator receives adisconnect signal caused by release of the connection at the substationB, she may clear out the connection by withdrawing the call and answerplugs 662 and GM, respectively, from the jacks l1 and 23, respectively.In response to this operation the established direct current bridgeacross the conductors of the trunk I0 is interrupted causing theenergization of the disconnect lamp provided in thecord circuit in usein the central oflice I0. The central omce operator may then clear outthe connection in the usual manner. If the central ofllce subscriber isthe first to abandon the connection, the central office operator mayclear out the connection in the usual manner and in so doing opens theloop circuit extending by way of the trunk 18 and the transfer trunk 22to the operator's cord circuit 660, thus causing the energization of thedisconnect lamp provided in this cord circuit. As a consequence, thebranch exchange operator is informed that the connection is ready forrelease and may clear out the connection by withdrawing the plugs 662and 661 from the jacks l1 and 23, respectively.

Call from order operators position to branch exchange switchboard If forany reason the operator attending the order operators position 2| findsit necessary to obtain information from one of the clerks or employeesnormally attending one of the branch exchange substations, she may causea connection to be routed to the branch exchange switchboard byoperating the call key 4220 to its off-normal position. In response tothis operation the contact spring-s 435 are engaged to prepare acircuit, traced hereinafter, for energizing the relay R440; the contactsprings 433 and 434 are disengaged to open the associated multiple pathover which ground potential is normally impressed upon the conductorC403; and the springs 433 and 432 are engaged to complete a circuit forenergizing the distributor start relay R6l0. This circuit extends fromground by way of the springs 433 and 432, RA44I, C480, the winding ofR6l0, RAGI3, the armature 652 and the winding of the magnet 65l tobattery. Due to the relatively high resistance of the winding oftherelay R610, the magnet l is insufliciently energized to operate whenthis circuit is completed. The relay R610, however, operates after aninterval to prepare, at RAGI2, a circuit for energizing the winding ofR620, the lower winding of R630 and the winding of R440 in series. AtRA6I3, the relay RBIO opens the path normally short-circuiting theresistor 615, thereby to insert further resistance in the above-tracedcircuit serially including its own winding and the winding of the magnet05L At RAG, the relay R610 opens an alternative circuit for energizingthe magnet 651 and completes an obvious circuit for energizing theslow-to-release relay R600. The relay R600, upon operating, prepares thealternative circuit for energizing the magnet 65L Assuming that thewipers of the distributor switch 640 are positioned in engagement withthe contacts corresponding to the trunk 26 and associated positionfinder 20, the relay R610 completes, at RASII, a circuit for energizingthe operating magnet 451 of the finder switch 450, this circuitextending from ground by way of RAGI I, RA03I, the wiper 646, C416 andthe winding of the magnet 451 to battery. The magnet 451, uponoperating, completes, at its armature 458, a circuit extendingby way ofC411 and the wiper 641 for energizing the upper winding of R630. Therelay R630'now operates to open, at RA63I, the operating circuit for themagnet 451, causing this magnet to release and advance the wipers 454 to456 inclusive, one step. At its armature 458, the magnet 451 opens thecircuit for energizing the relay R830. Accordingly, the

potential, as extended -tery., The resulting illumination relay R660restores to recomplete the circuit for energizing the magnet 451. Theinterrelated operation of the magnet 451 and the relay R630 continuesuntil the wipers 454 to 456, inclusive, are advanced into engagementwith the contacts terminating the conductor individual to the orderoperator's position 2|. When the wipers of the switch 450 are advancedto this position, the above-mentioned circuit is completed forenergizing the three relays R440, R620 and R630 in series, this circuitextending from ground by way of RA6I2, the winding of R620, the lowerwinding of R630, the wiper 648, C412, the wiper 456, the contact springs435 and the winding of R440 to battery. When this circuit is completed,ground through the winding of R620 and the lower winding of R630 to theleft winding terminal of the relay R440, is impressed upon the contactassociated with the wiper 401 which corresponds to the order operator'sposition 2|. This contact is multipled to the corresponding contacts ofeach of the other position finders having access to the order operator'sposition 2| so that all of these contacts are eflectively grounded,thereby to busy the order operator's position 2| to the various positionfinders. When the above-traced circuit is completed the relay R630 isheld operated independently of the magnet 451 so that the operatingcircuit for this magnet cannot be recompleted and operation of thefinder switch 450 is arrested. The relay R620 upon operating completes,at RA62I, a circuit for energizing the lowerwinding 01' R460, thiscircuit extending from ground by way of RA62 I, the wiper 650, C413 andthe lower winding of R460 to battery. Upon operating the relay R460completes a holding circuit for itself and the relay R440, this circuitextending from groundby way of the upper winding of A460, RA466, thewiper 456, the contact springs 435 and the winding of R440 to battery.The gro d potential, as extended through the upper w ding of R460 to theleft terminal of R440 also serves to mark' the operator's position 2| asbusy in the bank contacts of the various position finders individual tothe order trunks. At its armatures RA46| and RA462, the relay R460connects the talking conductors of the trunk 26 to the substationapparatus provided at the order operators position 2|. At

RA465, the relay R460 completes a circuit for energizing the call lamp663 individual'to the trunk line 26, this circuit extending from groundby way'of the jack spr n s 664, C416, RA465, C419 and the filament .ofthe lamp 663 to batof this lamp serves to inform the branch exchangeoperator that an incoming call on the trunk 26 should be answered. AtRA464 and its associated resting contact the relay R460 opens one of thepaths over which ground potential is normally impressed upon theall-trunks-busy conductor C415. At RA464 and its associated workingcontact the relay R460 completes a path including C414 for impressingground potential upon the test contact associated with the wiper 649which corresponds to the finder switch 450, thus identifying the trunk26 as busy in the bank contacts of the distributor switch and shortcircuiting the relay R6l0.

The relay R440 operates shortly following the operation 01 the threerelays R620, R666 and R466 and, upon operating, opens, at RA442, one ofthe multiple paths over which ground potential is normally impressedupon the conductor C466. At RA443 the relay R440 completes the 649 isdriven into engagement with the tact of the associated contact set. Whenan all-- erating circuit for the motor magnet 451, and to interrupt theoperating and holding circuits for the relays R620 and R630, causingthese two relays to restore. At RA6I4, the relay R6I0 opens theoperating circuit for the slow-to-release relay R600 and completes acircuit extending through RA60| for energizing the magnet "I of thedistributor switch 640 until the relay R600 releases. When energizedover this circuitthe magnet 651 attracts its armature 652 to open itstest circuit. At RA6I3, the relay R6l0, upon restoring, short circuitsthe resistor 6l5, thereby further to prepare the test circuit for thedistributor switch driving magnet 65L When the relay R600releases, themagnet 65| is deenergized and in cooperation with the associated ratchetand pawl mechanism steps the wipers 646 to 650, inclusive, intoengagement with the contacts corresponding to the next switch. In theevent the wipers 646 to 650 inclusive, are now standing on a set ofcontacts corresponding to an idle position finder switch, no furtheroperation of the distributor switch 640 occurs. On the other hand, itthe contacts engaged by these wipers terminate conductors extending to abusy position finder switch, ground potential is connected through theassociated test contact to the wiper' 649 so that the magnet 65l isagain energized and operates to advance the wipers a second step. Due tothe circuit interrupting action of the armature 652 the steppingoperation of the switch 640 continues until the wiper 649 is advancedinto engagement with a test contact from which ground is disconnected;that is, a test contact corresponding to an idle one of the positionfinder switches. When this occurs the stepping operation of thedistributor switch 640 is arrested, the wipers 646 to 650, inclusive,being left standing in engagement with the contacts corresponding to theselected idle position finder switch. If allof the finder switches arebusy at the time operation of the distributor switch 640 is initiated,the stepping operation of this switch continues until position finderlast conbusy condition or the position finders and associated trunkprevails, all of the relays corre sponding to and including the relayR466 individual to the position finder 29 and trunk' 26 are operated andthe conductor C415 is disconnected from ground. Accordingly, when thewiper 649 is operated to engage the contact terminating theconductor'C415 no further circuit is available for energizing the magnet65! and operation of the distributor switch 640 is arrested. Whenthereafter one of the position finders is released to cause therestoration of the relay embodied therein which corresponds to the relayR460 01' the position finder 29,ground potential is again impressed uponthe conductor C415 to again initiate the stepping operation of thedistributor switch the wiper 640, thisstepping operation continuinguntil the wipers 646 to 650, inclusive, are driven to the positioncorresponding to the position finder which has been released. Whentheidle position finder is found, the wiper 649 is disconnected from groundand the magnet 65| is deenergized; Following the hunting operation ofthe distributor switch 640, as described above, the distributor 30 isfully released and is conditioned to respond to the initiation of a callat another of the order operators positions.

When the branch exchange operator observes the illuminated condition ofthe lamp 663 indicating that a call is present on the trunk 26 she mayanswer the call by inserting the answer plug BM in the jack 28. Inresponse to this operation a talking circuit is completed between thecord circuit 660 and the telephone set in use at the order operatorsposition 2|. In addition, the jack springs 664 are disengaged tointerrupt the previously traced circuit energizing the call lamp 663.The branch exchange operator, after conversing with the order operatorattending the position 2|, may extend the connection to the desiredbranch exchange substation by inserting the plug 662 in the jackterminating the line extending to this substation and actuating theringing key embodied in the cord circuit 660 to project ringing currentover the line thus selected. For example, if the substation B is desiredby the order operator attending the position 2| the branch exchangeoperator may insert the calling plug 662 in the jack l1 and actuate herringing key, thereby to cause ringing current to be transmitted over theline l5 and through the windings of the ringer provided at thesubstation B. After the call is answered at the substation B the branchexchange operator may retire from the connection leaving the desiredtalking circuit established between this substation and the orderoperator's position 2|.

In order to release the connection thus established to the substation Bthe order operator attending the position 2| restores the call key 420to its normal position. In response to this operation the contactsprings 435 are disengaged to open the circuit including the winding ofR440 and the upper winding of R460, causing these two relays to restore.When the call key 420 is restored to normal the springs 432 and 433 arealso disengaged to open a further point in the path for impressingground potential upon the distributor start conductor C480. In addition,the contact spring 433 is moved into engagement with the contact spring434 to reprepare the multiple path, individual to the order operatorsposition 2|, over which ground potential is normally impressed upon theconductor C463. The relay R440 releasing, reprepares, at RA44I, the pathfor impressing ground potential upon the distributor start conductorC480 and recompletes, at RA442, the above-mentioned path, individual tothe order operator's position 2|, for impressing ground potential uponthe conductor C403. At RA443 the relay R440 opens the circuit forenergizing the busy lamp 424, individual to the order operators position2| and located at the supervisory operators position 32, thus indicatingto the supervisory operator that the order operators position 2| isagain idle. The relay R460, upon restoring, opens, at RA463, a furtherpoint in the above-traced holding circuit for itself and the relay R440.At RA46| and RA462 the relay R460 opens two points in the completed loopcircuit including the upper winding of the induc- 26 to the operatorscord circuit 660. The interruption of this loop circuit causes theenergization of the disconnect signal lamp provided in the operatorscord 'circuit 660, thus indicating to the branch exchange operator thatthe connection has been-cleared out at the calling operator's positionand may be released. At RA464, the relay Rd60 disconnects the markinglead C414 individual to the position-finder 29 from ground,

thereby to mark this finder as idle in the bank contacts of thedistributor switch 640. At RA464 and its associated resting contact, therelay R460 completes the multiple path, individual to the positionfinder 29, for impressing ground potential upon the all-trunks-busyconductor C415.

At RA465, the relay R460 opens a further point in the previously tracedcircuit for energizing the call lamp 663 individual to the tnmk line 26.The branch exchange operator, upon observing the lighted condition ofthe disconnect lamp included in the cord circuit 660, may clear out theconnection by withdrawing the plugs 66| and 662 from the jacks 20 andII, respectively. Thus, the apparatus utilized in setting up theconnection is fully released.

Call storage As indicated previously, the call storage circuit 3| inconjunction with the call storage position finder switches individual tothe order trunk circuits, are provided for the purpose of storing callsto the order operators positions when all of these positions are busyand for routing the stored calls to the order operators positions as theoperators positions are released in the order in which the calls arestored. More particularly, when all of the order operators positions areoccupied with calls or portions thereof are occupied with calls and theothers are not attended, the multiple paths individual to the variouspositions and over which ground potential is normally maintained uponthe common conductor C463 are all interrupted. As a result, the relayR540 is energized over a circuit extending from ground through thewinding of this relay and by way of C483, the contacts of the no-storagekey 422 and the resistor 484 to battery. When energized over thiscircuit the relay R540 operates to disconnect the wiper 5|5 of theswitch 5l0 from ground and to complete an obvious path for applyingground potential to the conductor C3H. This conductor is commonlyincluded in the operating circuits, traced hereinafter, for the relayR320 and the corresponding relays individually provided in the trunkcircuits respectively terminating the other order trunks extending tothe central oilice |0. The relay R540 is, at this time, the onlyoperated relay in the call storage circult 3|. Further, the call storagedistributor switch 500 may at this time occupy any one of itstwenty-four operating positions, while the wipers of the call releaseswitch 5l0 may occupy any one of a number of positions behind the po-RA513 to battery. At

R320 to battery. Due to the slow-to-operate characteristic of the relayR3" and the relatively fast operating characteristic of the relay R320,the last-mentioned relay operates to interrupt, at RA32I, the completedoperating circuit for the relay R3|0 before the latter relay canoperate. Since the relay R3| is prevented from operating, operation ofthe position finder switch 000 is not initiated in response to seizureof the associated trunk line [0. Further, with the relay R3l0 in itsrestored position the winding of the relay R300 is not bridged acrossthe conductors of the trunk line [0 to give the central oilice operatoranswering supervision in the manner previously explained. Also, theoperating circuit for the relay R320 is not opened and no circuit isprovided for energizing either of the windings of the stop relay R350.The relay R320 upon operating completes, at RA32I', an obvious path forbridging the winding of the relay R300 across the conductors of thetrunk I0 in series with the resistor 3l5, whereby the relay R300 is heldoperated through energization from the central ofllce battery. Theresistance value of the resistor 3l5 is such that the answer relay ofthe cord circuit in use in the central ofllce is not suflicientlyenergized to is completed. At RA323 and its associated resting contact,the relay R320 opens the path normally short-circuiting its lowerwinding. At RA322 and RA323, the relay R320 completes a locking circuitfor itself, which circuit extends from ground by way of RA330, RA322,the lower winding of R320 and the resistor M6 to battery. At RA324, therelay R320 completes a circuit extending by Way of C380 for energizingthe trunk call storage lamp 426 individual to the trunk l0, therebyindicating that a call present on the trunk line l0 has been placed instorage. At RA325, the relay R320 prepares a circuit, tracedhereinafter, for energizing the stop relay R330. At RA326, the relayR320 completes a circuit for energizing the relay R520, this circuitextending from ground by way of RA326, C313, the winding of R520 and IRA321 and its associated resting contact, the relay R320 opens a pointin the release or homing circuit for the operating magnet 369 of thecall storage finder switch 300. At RA321 and its associated workingcontact; the relay R320 completes a circuit for energizing the magnet369, this circuit ground by way of the restored armature RA532, C310,RA321, RA331, the armature 310 and the winding of the magnet 360 tobattery. Due to ,the circuit interrupting action of the armature 310,the magnet '36! operates buzzer fashion when the circuit just traced iscompleted and, in

' cooperation with its associated ratchet and pawl mechanism, advancesthe, wipers 365 to 360, inclusive, until thesewipersfind the positionmarked in the contacts of thecall storage position distributor switch500. Assuming, for example, that the wipers of the switch 500 stand inengagement with their respective associated fourth;

contacts, the wipers of the switch 360 are advanced three steps, atwhich time they also enextending from operate when this path to thesupervisory operator contacts. At RA336, the relay R330 completes anobvious locking circuit for itself. At M3", the relay R330 completes anobvious multiple path including the resistor M5 for bridging the windingof the relay R300 across the conductors ofthe trunk line l0. At RA332,the relay R330 opens a point in the above-traced operating circuit forthe relay R320 and connects multiple ground to the common conductor 3",thereby to insure the storing of a later initiated order tnmk callinitiated substantially simultaneously with the release of an orderoperator's position. At RA333 and RA330, the relay R330 transferslocking ground for the lower winding of the relay R320 to the operatedmake springs associated with RAI. At'RA335, the relay R330 prepares apath, traced hereinafter, for short-circuiting the lower winding of therelay R320 when an order operator's position becomes available.

When the relay R560 is energized in series with the lower winding ofR330 it operates after an interval to complete, at RA56I, a circuitextending by way of RA53I for energizing the operating magnet 501 of theswitch 500. When thus energized, the magnet 501 attracts its associatedarmature 508 to open the circuit through the winding of R560 and thelower winding, of R530. thereby to cause the release of the relay R560.This relay releasing opens the circuit forenergizing the magnet 501,whereby this magnet in cooperation with its associated ratchet and pawlmechanism steps the wipers 500 to 506, incluslve, of the switch 500 tothe next storage position. Since this next storage position is notoccupied with a stored call, the wiper 506 engages an open circuitedcontact and no further operation, of the relay R560 and the magnet 5010cours. The purposeof stepping the wipers of the switch 500 one step inthe manner just explained is to mark the next storage position of thisswitch as the position to be assigned to the next call routed over oneof the order trunks at a time when all of the order operators positionsare busy.

As indicated above, the relay R520 is energized and operates in responseto operation of the relay gage their respective associated fourthcontacts. 7

When the wiper 361 engages its associated fourth contact, a circuit iscompleted for energizing the lower winding of R330 in series with therelay R560, this circuit extending from ground by way of RA325, thelower winding of R330, the switch wipers 361 and 506 and theirrespective associated fourth contacts, the armature 500 and R320,immediately the call is initiated on the trunk line l0. The relay R520operating, completes, at RA52 I; an obvious circuit for energizing theoperating magnet. 5" of the switch "0. This magnet attracts its armature5" to com plete an obvious circuit for energizing the slowto-releaserelay R510. The relay R510 operating prepares, at HA5", a holdingcircuit for itself; prepares, at RA5I2, a circuit for energizing thelower winding of R550; and opens, at RA5'I3, the established operatingcircuit for the relay R520. The relay R520 releasing opens theestablished circuit for energizing the magnet 5. The magnet releasingadvances the wipers of the switch 5|0 one step and retracts itsassociated armature 5" to interrupt the operating circuit for the relayR510. The relay R510 releasing recompletes the operating circuit for therelay R520 which reoperates to again complete the operating circuit forthe magnet 5". The interrelated operation of the-two relays R520 andR510 and the magnet 5l1 continues until the wipers of the switch 5l0 arepositioned on the contacts marked by the setting of the call storagefinder switch 366. In the case assumed the wipers of the switch 366 arerapidly advanced to engage their respective associated fourth contactsin response to operation of the relay R326. Accordingly. the wipers ofthe switch are advanced to engage their respective associated fourthcontacts. When the wiper 5l6 engages its associated fourth contact, theabove-mentioned circuit is completed for enthe lower winding of R556,this circuit extending from ground at RA35'I by way of the wipers 366and 5l6 and their respective associated fourth contacts, M512 and thelower winding of R550 to battery. This circuit is completed while therelay R516 occupies its operated position and, accordingly, when therelay R556 operates the above-mentioned locking circuit for R516 isestablished, this circuit extending from ound by way of RA55I, RA5'H andthe winding of R516 to battery. Thus, the two relays R556 and R516 arelocked up under the control of the relay R356 to prevent any furtheroperation of the relay R526 and the magnet 5". At this point it is notedthat in the trunk circuit IS, the relays R366, R326 and R336 areoperated, while in the call storage circuit 3i the relays R566, R556 andR516 are operated. With the ap a atus in this condition no furtheroperation thereof occurs until one of the order operators positions isreleased, the stored call on the order trunk I6 is abandoned, or asecond call is routed over one of the order trunks.

If the call present on' the order trunk I6 is abandoned at the callingcentral ofllce subscrib ers substation prior to the release of one ofthe order operators positions and the established connection to the lineI6 is cleared out at the operators switchboard in thecentral exchangeII, the relay R366 restores. Upon restoring, this relay, at its armatureRA36I, opens the established locking circuit for the relay R326 andapplies multiple ground to the all-trunks-busy conductor C312. At RA362,the relay R366 opens a point in the previously traced operating circuitfor the relay R326. At RA363, the relay R366 interrupts the lockingcircuit for the relay R336. Thus, the two relays R326 and R336 arecaused to release. The relay R326 releasing Opens, at RA326, the circuitfor energizing the trunk call storage lamp 426; reprepares. at RA32I,the operating circuit for the relay R3l6; opens, at RA325, a furtherpoint in the operating circuit for the relay R336; opens, at RA326, thepath individual to the trunk circuit [6 over which ground potential isimpressed on the conductor C313; and, at RA32I,- opens a point in theinitially completed operating circuit for the magnet 36! and prepares analternative circuit for energizing this magnet. The relay R336 releasingopens, at RA33I, the path bridgin the winding of the relay R366 acrossthe conductors of the trunk l6; disconnects, at RA332, multiple groundfrom the common conductor C3"; reprepares, at RA332, the operatingcircuit for the relay R326; opens, at RA333 and RA336, an additionalpoint in the holding circuit for the relay R326; opens, at RA335, theprepared path for shortcircuiting the .lower winding of R326; opens, atRA336, a further point in its own locking circuit; and completes, atRA33I, the above-mentioned alternative circuit for energizing the magnet363. This circuit extends from ground by way of the wiper 365, themultipled contacts numbered from 2 to 25, inclusive, of the contact set36l, RA321, RA33I, the armature 316 and the winding of the magnet 36!!to battery. Due to the circuit in terrupting action of the armature 310,the wipers of the switch 360 are rapidly advanced step by step to theirrespective home positions at which time the wiper 365 engages itsassociated first contact. Since this contact is not connected to ground,the circuit for energizing the magnet 666 is interrupted and operationof the switch 366 is arrested. Thus, the wipers of the switch 360 areleft standing in their respective home positions. During this steppingoperation of the switch 366 and when the wiper 366 is disengaged fromits associated fourth contact, the previously traced operating circuitfor the relay R550 is interrupted causing this relay to restore and openthe locking circuit for the relay R516. As a result, the relay R510restores after an interval to reprepare the operating circuit for therelay R526. Under the circumstances assumed, wherein only the calloriginating on the order trunk 16 has been stored, ground potential isnot present on the common conductor C313 when the relay R616 restores.Accordingly, the'relay R520 is not reoperated to initiate operation ofthe switch 5". Following the operations just described, the order trunkcircuit i9 is fully restored to normal and all of the relays in the callstorage circuit, with the exception of the relay R540. are released.

If the order operator's position 2i is released while the calloriginating on the order trunk I6 is in storage, the relay R446 embodiedin the apparatus provided atthis position is released and the positionis marked as idle in the bank contacts of the position finders havingaccess thereto. The relay R440 releasing completes, at

RAHZ, its associated path for impressing ground,

potential upon the common conductor C463, thereby to short-circuit thewinding of the relay R540. The relay R540 releasing disconnects groundfrom the common conductor C3" and completes, at RAE, the previouslymentioned path for short-circuiting the lower winding of R326, this pathextending from ground by way of RA56I, the wipers 5i5 and 366 and theirrespective associated fourth contacts, RA335, the lower winding of R320,RA323, RA322, RA336, RA333 and RA30I backto ground. When thusdeenergized, the relay R326 releases to short-circuit its lower windingand open the short-circuiting path just traced. At RA324, the relay R320opens the previously traced circuit for energizing the trunk callstorage lamp 626, thereby indicating to the supervisory operatorattending the position 32 that the call present on the order trunk l6has been released from storage. At RA325, the relay R320 opens a furtherpoint in the previously traced circuit for energizing the lower windingof R330 and the winding of R566 in series. At RA326, the relay R326opens the associated path for impressing ground potential on theconductor C313. At RA32I, the relay R326 opens a further point in theinitially completed operating circuit for the magnet 369 and preparesthe above-traced alternative circuit for energizing this magnet. At RA32i the relay R320 completes the previously traced operating circuit forthe relay R3". The relay R3i0 operating bridges the winding of the relayR300 directly across the conductors of the trunk i8, thereby to causethe operation of the answer relay provided in the operator's cordcircuit in use in the central oilice I0. The relay R3i0 operating, alsoinitiates operation of the position finder 660 to find the orderoperator's position 2i which has been released, all in the mannerpreviously described. At M3, the relay R3" opens a point in thepreviously traced operating circuit for the relay R320. When the wipersof the position finder 400 are positioned on the contacts correspondingto the operator's position 2|, the relays R350 and R040 are energizedand operate in the manner hereinbefore described. The 'relay R350, inoperating performs the functions previously described, and, in addition,opens, at RA355, the established looking circuit for the relay R330permitting the latter relay to release. At RA351, this relay R35 opensthe previously traced operating circuit for the relay R550, thereby tocause the sequential release of the relays R550 and R510 in the ordernamed. Thus, the apparatus provided in the call storage circuit 3kg;fully restored to normal. It is to be noted that if none of the otherorder operators positions have been released substantiallysimultaneously with the release of the order operators position 2|, therelay R440 in operating opens the only completed multiple path forimpressing ground potential upon the common conductor C453. As a result,the operating circuit for the relay R540 is reestablished and this relayoperates. with the relay R540 operated, further calls routed over theorder trunks to the order operators positions are stored until such timeas a corresponding number of the order operators positions are released.

The relay R330 releasing opens, at RAMS, RA! and RA332, additionalpoints in the previously traced operating, holding and release circuitsfor the relay R320; opens, at RA335. a further point in its own lockingcircuit; opens, at RASSI, the initially completed path for bridging thewinding of the relay R300 across the condoctors of the trunk I0;disconnects, at RA332, the conductor 31! from ground; and reprepares, atRA332, the operating circuit for R320. At RA331, the relay R330completes the previously traced alternative circuit for energizing themagnet 359, causing this magnet, in cooperation with its associatedratchet and pawl mechanism, to advance the wipers 365 to 358, inclusive,step by step until they are moved to their respective home positions.Following the operations just described, the desired connection betweenthe central oflice subscriber's substation and the order operatorsposition 2| is fully established. This connection may be routed to thebranch exchange switchboard or through this switchboard to one of thebranch exchange substations or may be released under the control of theoperator attending the position 2|, all in the manner previouslydescribed.

In the event a plurality of calls intended for the order operatorspositions are routed over the order trunks at a time when all of theorder operators positions are busy, these calls are assi ned successivestorage positions by the switch 500. In this regard it will be recalledfrom the previous explanation that the wipers of the switch 500 wereadvanced one step to a new call storage position in response to storageof the call routed over the order trunk It. More specifically, thesewipers were advanced to engage their respective associated fifthcontacts. If, with the wipers of the switch 50. standing in thisposition, a second order trunk call is initiated prior to the release ofone of the order operators positions the trunk circuit apparatusassociated with the order trunk in use operates in substantially themanner described above with reference to the order trunk circuit l9,except that the wipers of the call storage finder switch embodied in.the

second trunk circuit are operated to engage their respective associatedfifth contacts and are left standing in this position. Following suchoperation of the second call storage finder switch, the wipers of theswitch 50l are advanced an additional step and are left standing inengagement with their respective associated sixth contacts. With thesewipers in this position a third order trunk call initiated prior to therelease of any of the order operators positions is assigned the sixthstorage position under the control of the wipers embodied in the switch500. It wilh thus be apparent that order trunk calls initiated at a timewhen an all-busy condition of the order operators positions prevails areassigned successive storage positions under the control of the switch500.

The purpose of the switch 510 and its associ ated control apparatus isto release the calls from storage in the same order as they are stored.Thus, it in the case considered above a plurality of the trunk calls arestored prior to the release of the order operator's position and thecall on the order trunk 10 is the first call stored, the orderoperator's position 2| is assigned to the use of the order trunk it.This is true for the reason that the relays R550 and R510 are heldlocked up under the control of the relay R350 regardless of the numberof steps taken by the wipers of the switch 500 following the locking upof these two relays. Under these circumstances,

when the relay R350 operates in response to op-.

eration of the position finder 00 to seize. the order operator'sposition 2!, it opens the established operating circuit for the relayR550 causing the latter relay to release and open the establishedlocking circuit for the relay R510. The relay R510 restores after aninterval to recomplete, at RA513, the operating circuit for the relayR525. This latter relay operating completes the circuit for energizingthe magnet 511 which magnet, in turn, completes the operating circuitfor the relay R510. The relay R510 operating opens the operating circuitfor the relay R520 to cause the sequential restoration of the latterrelay and the magnet 511, whereby the wipers 5 to 5l8, inclusive, areadvanced to engage their respective associated fifth contactscorresponding to the second stored call. If this call has not beenabandoned, ground potential is present upon the fifth'contact oi thecontact set 5|: as a consequence of the setting of the call storagefinder switch individual to the order trunk over which the second storedcall was routed. Accordingly, the relay R550 reoperates to close thelockingcircuit for the relay R510 and thus prevents further operation ofthe relay R520 and the magnet5l1. The relays R550 and R510 are thuslocked upnnder the control of theground potential is not present uponthe contact of'the set 513 which corresponds to the second stored call,namely, the fifth contact of this set. Accordingly, a second cycle ofoperation of the two relays R510 and R520 and the magnet 5" occurs sothat the wipers of the switch 5| 0 are advanced to engage theirrespective associated sixth contacts. If the stored call correspondingto this position of the switch 510 has also been abandoned the cyclicoperation of the two relays R510 and R520 and the magnet again occurs toadvance the wipers of the switch 5l0 into engagement with theirrespective associated seventh contacts. When the position of the switch5" corresponding to the next call in storage is found, the relays R550and R510 are locked operated under the control of the relay whichcorresponds to the relay R350 and is embodied in the trunk circuitassociated with the order trunk on which this call is present.

If a stored order trunk call next to be released from storage by thecall storage circuit 3| is abandoned before an order operators positionbecomes available the call release switch 5I0 is automatically advancedto the position corresponding to the next stored call, assuming thatadditional order trunk calls are in storage. Thus, if a trunk calloriginating on the trunk is one of a number of order trunk calls instorage, the switch 5" occupies a position corresponding to the call onthe trunk I8 and this call is abandoned, the trunk circuit apparatus I5is caused to be released in the manner previously described. During therelease of this apparatus the wipers of the switch 350 are restored tonormal under the control of the magnet 350.

This homing operation on the part of this switch 350 results in theremoval of ground potential from the contact of the set 364 whichcorresponds to the position occupied by the wipers of the switch SN and,hence, the relay R550 is deenergized and restores. This relay restoringinitiates the cyclic operation of the two relays R510 and R520 and themagnet 5| 1 in the manner previously explained, thus causing the wipersof the switch 510 to be operated step by step until the contactscorresponding to the next stored call are engaged thereby. When thewipers of the switch 5l0 reach the position corresponding to the nextcall in storage, the relays R550 and R510 are locked up under thecontrol of the relay corresponding to the relay R350 and embodied in thetrunk circuit associated with the order trunk on which the next storedcall is present.

In order to prevent useless operation of the switch 500 when more thantwenty-three of the call storage positions thereof are occupied withstored calls and to prevent later initiated 'calls from obtainingpreferred storage positions, an arrangement comprising the slip multipleextending between the contact sets SM and 503 of this switch isprovided. More specifically, this slip multiple is such that when thewiper 504 engages any of its associated contacts except the first, it isconnected by way of one of the conductors of the multiple to the contactnext succeeding the engaged contact and provided in the contact set 503.To this end, the second contact of the set 503, which corresponds to thefirst storage position of the switch 500, is connected to thetwenty-fifth contact of the set 50l and the contacts numbered from 3 to25, inclusive, of the contact set 503 are respectively connected to thecontacts numbered from 2 to 24, inclusive, of the contact set 50!. Withthis arrangement it call storage is started and all but one of thetwentyfour available storage positions are subsequently assigned at atime when no order operators positions are available, the wiper 504 willbe connected to a grounded contact in the contact set 503. Thus, if thewipers 504 to 505, inclusive, occupy positions in engagement with theirassociated third contacts when the next to last storage position isfilled, these wipers will not be advanced from this-position. Underthese circumstances ii the wipers of the finder switch 300, for example,occupy positions in engagement with their associated fourth contacts,corresponding to the fourth storage position of the switch 500, groundpotential is extended from RA325 through the lower winding of R330 andthe wiper 301 to the fourth contact of the contact set 503. Accordingly,a circuit is completed for energizing the relay R530, this circuitextending from the grounded fourth contact of the set 503 by way of thethird contact of the set 5", the wiper 504, C402, the contacts of thestep-0n switch 42l, 040i and the winding of R530 to battery. The relayR530 operating disconnects ground from the conductor C314 commonlyincluded in the various operating circuits for the motor magnets of thestorage position finder switches corresponding to and including theswitch 350, thereby to prevent any of these switches which areassociated with idle order trunks from being operated. At RA53I, therelay R530 opens a point in the above-traced operating circuit for themotor magnet 501, whereby operation of the distributor switch 500 isprevented. With the apparatus in this condition if an order trunk callis initiated, the relays embodied in the trunk circuit associated withthis trunk line, which correspond to the relays R300 and R320 of thetrunk circuit l3, are caused to operate, the last-mentioned thereoffunctioning to complete a locking circuit for itself. Following theoperation of these two relays the trunk circuit in use remains locked upuntil the call routed thereover is abandoned or until a call storageposition becomes available in the switch 500 through the release of oneof the previously stored calls from storage.

The relay R530 remains operated until such time as the stored callcorresponding to the storage position of the switch 500 next succeeding.that occupied by the wipers of this switch is released from storage. Itwill be apparent from the foregoing explanation that this stored callwill be the next call to be released from storage under the control ofthe switch 510. When this call, which, as was stated above, is presenton the order trunk I0, is released from storage," the relay R320 iscaused to release and the switch 350 is automatically restored to itshome position, all in the manner previously explained. The relay R320releasing disconnects ground from the third contact of the contact set503 in the switch 500 and in so doing interrupts the previously tracedoperating circuit for the relay R530. The relay R530 releasing,preparesat RA53I, the operating circuit for the magnet 501. At RA532,the relay R530 again connects the common conductor C314 to ground sothat if an unstored call is present on one of the order trunks a circuitis completed for energizing the motor magnet of the call storage finderswitch associated with the trunk on which the unstored call is present.This finder switch operates to advance its wipers into engagement withtheir associated third contacts at which time the previously describedtrunk circuit relay operations occur to place the unstored call instorage. Incident to these trunk circuit relay operations, groundpotential is impressed upon the third contact of the contact set 503 tocause the sequential operation of the relay R550 and the magnet 501allowed by the release of these two circuit controlling devices.

so that the wipers of the switch 500 are advanced into engagement withtheir respective associated fourth contacts. At this time ground isagain applied over one of the slip multiple conductors to the wiper 504so that the relay R530 is reoperated to perform the functions previouslydescribed. From the foregoing explanation it will be apparent that whiletwenty-four storage positions are actually provided in the switch 500only twenty-three of these positions can normally be usedsimultaneously. It will further be apparent that the slip multiplearrangement between the contact sets M and 503 of the switchIllfunctions to prevent useless operation of this switch when all of thestorage positions are filled and to prevent later initiated order trunkcalls from obtaining preferred storage positions in the switch 500, thusinsuring the release of the calls from storage in the same order as theyare stored.

In order further to prevent unnecessary delay in releasing calls fromstorage an arrangement is provided for preventing the wipers of theswitch 5l0 from being operated to a position in advance of the positionoccupied by the wipers of the switch 500. In this regard it will berecalled from the foregoing explanation that when all of the orderoperators positions are busy the,s relay R50 is operated. With thisrelay operated, if a call originates on the order trunk iii,

the relay R320 of the trunk circuit I9 operates to complete thepreviously traced operating circuit for the relay R520, thereby toinitiate the stepping operation of the switch 5l0. Simul taneously withthe initiation of operation of the switch 5l0, operation of the switch350 is initiated in the manner previously explained. It the operation ofthese two switches is initiated at a time when the wipers of the switch500 are engaging their respective associated twenty-fourth contacts,twenty-four steps on the part of the switch 350 are required to positionthe wiper 358 on the associated twenty-fourth contact to com plete thecircuit for energizing the stop relay R550 associated with the switch5l0. on the other hand, if the wipers of the switch are engaging theirassociated twenty-third contacts when operation of the switch 5|0 isinitiated, only three steps are required on the part of the switch H0 inorder to advance the wipers of this switch to a position beyond thatoccupied by the contact of the set 5 is connected to the second contactof the contact set 502 and the contacts numbered from 2 to 24,inclusive, of the contact set 5 are respectively connected to thecontacts numbered from 3 to 25, inclusive, of the contact set 502. Withthis arrangement an alternative circuit is provided for energizing therelay R550 each time the wipers of the switch 5| 0 are advanced to aposition one step behind the position occupied by the wipers of theswitch 500 at a time when. an order trunk call is to be placed instorage. Thus, in the foregoing illustration wherein a call originatingon the order trunk I8 is assigned to the twenty-fifth storage positionof the switch 500, ground potential is impressed upon the conductor C313through operation of the relay R320 in the manner previously explainedand the stepping operation of the two switches 350 and H0 issubstantially simultaneously initiated. When, however, the wipers of theswitch 5l0 have been advanced to engage their associated twenty-fourthcontacts the above-mentioned alternative circuit is completed forenergizing the relay R550 regardless of the position occupied by thewipers of the switch 350. This alternative circuit extends from groundby way of RA320, C313, the wiper 505 and its associated twenty-fifthcontact, the wiper 5| 4 and its associated twenty-fourth contact, andthe upper winding of R550 to battery. When this circuit is completed therelay R550 operates to complete the previously traced locking circuitfor the relay R510, thereby to arrest the stepping operation of theswitch H0 in the manner previously explained. When thereafter the wipersoi the switch 500 are advanced to the next sucwipers of the switch 500.In such case a complete cycle of operation of the switch 5|0 isobviously required before the wiper 5l6 engages the contact in thecontact set 5l3 which has been marked through operation of the switch350 to cause the operation ,of the stop relay R550- Although thestep-by-step operation of the switch 5| 0 is relatively slow as comparedwith that of the storage position finder switchesindividual to the ordertrunk circuits, it is easily possible for the wipers of the switch 5l0to be advanced three or more positions while the wipers of the switch350 are being advanced through twentyfour or less positions. Hence, itwould be possible for a substantial time interval to elapse between therelease of an order operators position and the release 'of a call fromstorage.

In order to obviate the difl'iculties outlined in the precedingparagraph, there is provided an arrangement which comprises a slipmultiple extending between the contacts of the contact set502 embodiedin the switch 500 and the contacts of the contact set 5 embodied in theswitch 5". More specifically the twenty-fifth ceeding storage position,in the manner previously described, the alternative circuit forenergizing the relay R550 is interrupted at the wiper 505 and itsassociated twenty-fifth contact. By this time, of course, the wipers ofthe switch 350 have been positioned in engagement with their respectiveassociated twenty-fifth contacts representing the storage positionassigned to the "trunk circuit 10 by the switch 500. Also, groundpotential is still present upon the conductor-C313 so that when therelay R550 releases the relays R510 and R520, in cooperation with theoperating magnet 5", function to cause the wipers of the switch M0 to beadvanced into engagement with their respective associated twenty-fifthcontacts. At this time a circuit extending from ground at RA351 andthrough the wipers 368 and 5|5 is completed for again energizing therelay R550. -This,relay in reoperating completes the locking circuit,for the relay R510, thereby to prevent further operation of the switch5l0. From the foregoing explanation it will be apparent thatthe'provision of the slip multiple between the contact sets 502 and 5Hpositively precludes the possibility of the wipers of .the switch 5|0from 7 being advanced to a. position ahead of the position occupied bythe wipers of the switch 500.

Supervision As indicated previously, apparatus is provided at thesupervisory operators position 32 whereby this operator may maintain aclose check on the condition of the order operators positions and thevolume of-traiiic routed over the order trunk lines. Thus, provisionsare made whereby the operator may monitor any connection involvinganyone of the order operators positions. To this end, the jack 9| isprovided, the springs of which are connected by way of the conductors

